Clockwork precision and how India entered Mars orbit

Bangalore, Sep 24: An Indian spacecraft Wednesday entered into Mars orbit in its maiden attempt by executing the crucial operation precisely to create history.

The final operation began at 4.17 a.m. when the spacecraft's medium antenna was first activated for signals and it was rotated towards Mars at 6.57 a.m.

"The 440 Newton liquid apogee motor (LAM) was fired at 7.17 a.m. and its burn started on dot at 7.30 a.m. as programmed for the crucial operation," a senior space scientist told IANS at the Mars mission control centre here.

Test firing of the LAM for nearly four seconds Monday, nine months and 21 days after it was shut Dec 1, 2013, enabled it burn as intended for insertion.

"The burn was terminated at 7.54 a.m. when the required braking velocity was achieved and the spacecraft was reoriented to point its antenna towards earth for resuming communication with ground stations," the scientist said.

The Orbiter's speed was also reduced by 2.14 metres per second from 22.2 km per second for its smooth transition into Mars orbit from Sun orbit.

The burn took place when there was a solar eclipse on Mars for 15 minutes. As a result, radio link between the spacecraft and earth stations snapped.

"As the accelerometers onboard were programmed in advance, the commands were executed automatically," the scientist claimed.

The eclipse occurred owing to Mars, sun and earth geometry (moving on same axis) five minutes after burn started (7.35 a.m.).

"As the spacecraft entered the eclipse phase, we had to re-orient it to align the thrust vector before firing the engine along with its eight small thrusters to reduce its speed," the official added.

The spacecraft is cruising in an elliptical orbit 427 km from Mars surface (perapsis) and 78,500km away from it (apoasis).

The Orbiter will take 77 hours or 3.2 earth days to rotate around the red planet over the next six months and for studying its surface and mineral composition and scan its atmosphere for methane gas in search of life-sustaining elements.